As it happens renewables are actually less variable than nuclear or coal over the short term. The UK National Grid has done a lot of work in this area and concluded that renewables are more reliable. The simple fact is that if the wind is blowing at 20 km/h now it will only vary by 1-2 km/h over the next 15 minutes. If a turbine fails you lose a few megawatts. If a cloud passes over your solar PV output only drops slightly, unless it is a large cloud front which is also easily predictable. Compare that to say nuclear where if a turbine goes down you like lose 500MW or more instantly and without any warning, meaning you need much more spare capacity on-line all the time.

I disagree, while you can lose blocks of large generation quickly it is fully manageable because all credible scenarios are catered for, mainly with pumped storage and contracted frequency response from conventional generation.

The UK Grid System Operator gets paid an 'incentive bonus' by the UK regulator for accurate forecasting of the output of the grid connected wind turbines hence it is in their interests to get it right. This is near real time data, the following figures are applicable to today 11th November 2014 but a similar pattern is visible on many days as weather systems pass over the UK with a wide variation of wind speeds.

Scroll down to Wind Forecast Out-turn, hover over the red line at Period 35 6239MW, that is what was actually produced on average during that particular half hour period around 6pm.

The latest Forecast value, the green bar for Period 35 , made at UTC 2100 the day before predicted 5487MWThe initial forecast made two days before for Period 35 was 4004MWA difference of 752MW a day ahead and 2235MW two days ahead.That is on a grid connected wind total of 8403MW

Many would call that quite unpredictable, the fact it produced more than predicted is immaterial, regardless of direction of the error it always leads to conventional plant operating in a less than optimal operating regime. The temperature corrected demand predictions made by the grid system operator are in the main extremely accurate, based as they are on vast amounts of historical data.

The facts are that wind turbine output remains extremely unpredictable, even with the latest forcasting techinques costing many millions of pounds and with a multi-million pound incentive carrot dangling in front of a commercial grid system operator.

Personally I'd much prefer a minimum of 30GW of modern nuclear for base load topped up with coal and gas over a landscape obliterated with white elephant subsidy grabbing, tax exempt, unpredictable, unreliable, useless wind turbines.

The controller itself has a published price of about a dollar. So maybe it's $.50 in volume. Add a $.50 MOSFET and do that for each of the 36+ cells on a typical panel and you have one very expensive solar panel. I'm still betting that the bypass diodes are done on a string basis of approximately 15-18 cells per "diode" - ideal or actual.

Well, the volume prices should be lower than that, but by the time you mount them on a little board with a few passives and connectors I guess its a bit expensive on a per cell basis. It is, however, very practical to spread them across an array in much greater numbers than you would spread 0.7V drops.

Dave, any reference for the claim that 50% of Germany's electricity supply comes from solar?

There are loads of references for the fact that 50.6% of Germany's electricity supply came from solar during a one hour period on the 9th of June this year. It was an exceptional figure, since it was a very sunny day and a national holiday, with unusually low demand.

Journalists being journalists, there are plenty of headlines with more extravagant claims, and I guess Dave may have seen one of these.

that is the key, it was just a brief peak, so when dave mentions 50% it's kinda misleading, not even germany is remotely close to being at that figure...ballpark or not...

more important numbers are:

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In the first quarter of 2014, renewable energy sources met a record 27 percent of the country’s electricity demand, thanks to additional installations and favorable weather. “Renewable generators produced 40.2 billion kilowatt-hours of electricity, up from 35.7 billion kilowatt-hours in the same period last year,” Bloomberg reported. Much of the country’s renewable energy growth has occurred in the past decade and, as a point of comparison, Germany’s 27 percent is double the approximately 13 percent of U.S. electricity supply powered by renewables as of November 2013.

i would like to see how much renewables participate in energy output in winter.probably way under 27%.would also like to know how many germans rely on electricity for heating, that way i could tell you will they be able to reach goal of 80% of renewables by 2050...

Germany is looking to reduce CO2 output by 40% by the mid 2020s. They are on target for that, reducing the number of coal plants and replacing old ones with new cleaner ones.

What are currently termed clean coal and clean coal boilers put out slightly more CO2 than other coal systems. They are considered clean because they only produce CO2 instead of a nasty cocktail of things.

What are currently termed clean coal and clean coal boilers put out slightly more CO2 than other coal systems. They are considered clean because they only produce CO2 instead of a nasty cocktail of things.

They are using carbon capture for the CO2, and eventually even those plants will be run down. As it is they don't think that the new ones will ever make any money. I think they will probably be nationalized at some point, or at least the operators will go from making a profit on the output to being paid to keep them running as backup for renewables that supply the majority of energy. Public ownership of the grid has already begun to happen.

Do you have any information on that? I thought there had only been pilot projects for CO2 sequestration, either abandoned before completion or after some experimental operation. I've been Googling and I can still only find one abandoned German project.

Do you have any information on that? I thought there had only been pilot projects for CO2 sequestration, either abandoned before completion or after some experimental operation. I've been Googling and I can still only find one abandoned German project.

A loss of 10% of a nation's generation capacity due to a single fault is pretty lousy design.

Which is why they need distributed renewables.

Their current problem has nothing to do with the need for renewables. They appear to have a single point of failure taking all the generating sets in a large site down in one go. That should have been structured as independent units for each generating set, or at least a common facility with some redundancy.

A loss of 10% of a nation's generation capacity due to a single fault is pretty lousy design.

Which is why they need distributed renewables.

Only if they want electricity when it is sunny, or the wind is blowing within a defined speed range, or they flood the land they feed themselves with, or flood that of their neighbour, or consume enough goods produced elsewhere in the world to be able to burn the packaging, or replace all the food producing land with biofuel crops.

I'm not one for polluting the planet just to keep the lights on. I certainly recognise that hydrocarbons are somewhat limited in quantity at the price the consumer is willing to pay, and that hydrocarbons are the only viable choice for a number of forms of transport, but renewables are not IMHO the solution and some are actually contributing to the problem by unstablising the incentive to make a long term investment in generation that will reliably deliver round the clock every day of the year for three generations or more.

Renewables actually work quite well off grid when you know their limitations and there really is no other viable alternative. For the rest of mankind, living in the developed world they are a solution espoused by the vocal blinkered few that IMHO will end up with the economies of entire countries and continents collapsing in their desire 'to save the planet' That governments have forced consumers in many countries to subsidise their deployment is IMHO obscene.

After reading through this thread and seeing how many people have misunderstood Dave's point. Here's another way of putting it. In economics one of the most rudimentary things to understand is opportunity cost. Opportunity cost is the reasoning Dave is using here. For example, lets say that you start an engineering contracting company and you're able to take home a salary of $50,000. Anyone in their right mind would say that this business is viable and that you are successful. But say that if you were to not have that business you would work for an established company as an engineer and be able to make $70,000. It no longer makes any economical sense to keep your business as your opportunity cost of owning that business is $70,000 giving you a profit of -$20,000. The opportunity cost of running that business is your next best source of income which is in this case GREATER than what you're currently making leaving you with a negative profit. To apply this to solar roadways, it does not matter how efficient solar panels get or if a solar roadway is able to make a positive profit, the opportunity cost of building these solar roadways will always be huge as these panels could generate 5x the output in their intended orientation. Even if a solar road is able to make a $500 profit each year, it's opportunity cost will be $2500 which gives us a NEGATIVE profit of $2000 when using solar panels as a road. Now say a new solar panel comes out that can make $1000 a year as a road, great! But you could still be making $5000 using these in their most efficient orientation. The opportunity cost of using them as roads is $4000.

Renewables actually work quite well off grid when you know their limitations and there really is no other viable alternative. For the rest of mankind, living in the developed world they are a solution espoused by the vocal blinkered few that IMHO will end up with the economies of entire countries and continents collapsing in their desire 'to save the planet' That governments have forced consumers in many countries to subsidise their deployment is IMHO obscene.

Some on-grid renewables make excellent sense, because they have natural compatibility with people's needs. For example in Texas there is considerable wind. It is predominantly a nightime event, and that's when people's cars are available for charging. So, if a culture of electric cars can be developed, and those cars support rapid load shedding commands, you could have a pretty good renewable energy scheme. Of course, there will be times when customers are becalmed long enough to feel like the tall ship crews of old, but at least there is a natural cure for the short term storage problem, because the loads have appropriate flexibility.

At the other end of the spectrum is this project near Eindhoven in the Netherlands. Not entirely off topic as the other idea of solar roadways was trying to light up the roadway, but I don't believe they're using solar panels to power the path way.

After reading through this thread and seeing how many people have misunderstood Dave's point. Here's another way of putting it. In economics one of the most rudimentary things to understand is opportunity cost. Opportunity cost is the reasoning Dave is using here. For example, lets say that you start an engineering contracting company and you're able to take home a salary of $50,000. Anyone in their right mind would say that this business is viable and that you are successful. But say that if you were to not have that business you would work for an established company as an engineer and be able to make $70,000. It no longer makes any economical sense to keep your business as your opportunity cost of owning that business is $70,000 giving you a profit of -$20,000. The opportunity cost of running that business is your next best source of income which is in this case GREATER than what you're currently making leaving you with a negative profit. To apply this to solar roadways, it does not matter how efficient solar panels get or if a solar roadway is able to make a positive profit, the opportunity cost of building these solar roadways will always be huge as these panels could generate 5x the output in their intended orientation. Even if a solar road is able to make a $500 profit each year, it's opportunity cost will be $2500 which gives us a NEGATIVE profit of $2000 when using solar panels as a road. Now say a new solar panel comes out that can make $1000 a year as a road, great! But you could still be making $5000 using these in their most efficient orientation. The opportunity cost of using them as roads is $4000.

Thanks for the videos and math Dave. Keep 'em coming

If that is what Dave really meant than all right, true and true. But the problem was that he deliberately went out of the way to explain that the whole concept is to put solar panels to the most hostile environment possible and because of that it will never be sustainable. I think that most people took offence in. I dont think anyone can really argue with the math he presented. It is valid and precise in My opinion (which isn't mean a rats ass). With the currently available technology it not pay for it self or even sustain itself.

Using solar cell isn't best way to keep snow of the road. I would put tube of liquid, like water. You get this liquid to flow down to a large body of water. In summer time it would heat the water up while in the winter it would keep the road over 4 deg C. I not sure how big of water source you need. LED in the road is stupid, if there is such a thing, use reflectable e-ink instead because it only uses power when changes are done but I don't know how to protect them.Keep up the good work.

Some on-grid renewables make excellent sense, because they have natural compatibility with people's needs. For example in Texas there is considerable wind. It is predominantly a nightime event, and that's when people's cars are available for charging. So, if a culture of electric cars can be developed, and those cars support rapid load shedding commands, you could have a pretty good renewable energy scheme. Of course, there will be times when customers are becalmed long enough to feel like the tall ship crews of old, but at least there is a natural cure for the short term storage problem, because the loads have appropriate flexibility.

So it's windy at night, but it's not windy every night, nor all the year round. For the nights when it isn't windy all these vehicles become immovable objects next day, or you have to run 'conventional' generation to charge the batteries, or watch your economy collapse when people can't go to work. Lets just plug some figures in. Car population in the USA is roughly 0.8 per capita, or for 26 million persons in Texas around 20 million vehicles. Assume 25% market penetration of electric vehicles of a similar type to the current Tesla S, whose batteries are 85kWh giving a storage potential of 425GWh, a big number, sounds impressive, but what happens when the wind doesn't blow, assume 15% top charge up required every day, and an 8 hour 'slow' charge. Roughly 9GW of generation is required.

Cost of 9GW of generation sits around doing nothing on the offchance the wind doesn't blow, or blows too hard, around 9 billion dollars (for CCGT Gas) and that is just the capital cost, not the fuel. 500 million dollars in interest payments alone at around 5% the shareholders will demand.

Wind turbines meanwhile operate at a real world capacity factor of around 20%, so to meet that 9GW demand it requires 45GW of wind turbine capacity. Cost of that is around 1.6 million dollars per MW capacity (3MW turbine Vestas / Siemens or 4.8 million dollars per turbine) 45GW requires 15000 wind turbines or 72 billion dollars, 3.6 billion dollars in interest payments alone at 5%

A total of 81 billion dollars capital invetsment required to support a population of 5 million vehicles. 16000 dollars per vehicle.

Lots of figures, all roughly in the right ballpark but one thing that keeps cropping up time and time again. Why pay for two sources of energy when just one will do. Mines a nuke. Sits there for months on end just doing the job round the clock. Lasts half a century or more, the entire 'waste' of a 1GW station fits in less space than an olympic swimming pool or can be recycled many times (although digging for new ore and processing it is cheaper) Meanwhile the horizon is unspoilt, there is no noise, the lights stay on.

Some on-grid renewables make excellent sense, because they have natural compatibility with people's needs. For example in Texas there is considerable wind. It is predominantly a nightime event, and that's when people's cars are available for charging. So, if a culture of electric cars can be developed, and those cars support rapid load shedding commands, you could have a pretty good renewable energy scheme. Of course, there will be times when customers are becalmed long enough to feel like the tall ship crews of old, but at least there is a natural cure for the short term storage problem, because the loads have appropriate flexibility.

So it's windy at night, but it's not windy every night, nor all the year round. For the nights when it isn't windy all these vehicles become immovable objects next day, or you have to run 'conventional' generation to charge the batteries, or watch your economy collapse when people can't go to work. Lets just plug some figures in. Car population in the USA is roughly 0.8 per capita, or for 26 million persons in Texas around 20 million vehicles. Assume 25% market penetration of electric vehicles of a similar type to the current Tesla S, whose batteries are 85kWh giving a storage potential of 425GWh, a big number, sounds impressive, but what happens when the wind doesn't blow, assume 15% top charge up required every day, and an 8 hour 'slow' charge. Roughly 9GW of generation is required.

There are plenty of problems with the West Texas wind farm idea, but I think you are seeing problems in the wrong places. I think that in general wind power is a stupid idea, unless you come up with some seriously effective storage scheme, which can get you over really long periods of low energy input to the system, and can smooth out the short term highs and lows. However, this focused West Texas car charging wind farm idea has been proposed by utilities who see real commercial potential in it. Texas isn't the kind of place to promote ideas which don't stand scrutiny on purely economic grounds. On the other hand, they do have some offerings to consumers which are hard to figure out. In some parts of Texas you can pay a fixed monthly fee, and have unmetered power at night. So, if you use enough nighttime power for this package to be effective for you, you might as well leave every aircon, car charger and water heater running as much as you can.

I think the Texan average daily drive requires more than a 15% top up each night, so your figures for the kWh needed each night is probably low. You can charge from the time the wind rises, as the light fades, and the time people get up for work. You don't need to wait for the evening domestic usage to fade, as people go to bed, as the wind power is an additional source. I think Texas creates problems with the waking time, as a lot of Texans start work really early and finish early. Its hard to distinguish these when charging, so you really need to complete each night's charging by quite an early hour. Another issue is with a scheme which assumes that on still nights you could end with the cars not fully recharged. Anyone who is simply commuting that day is probably fine with leaving home with a half charged car. Someone making a long journey that day will be less than happy. Again, distinguishing these during charging is difficult, although commiting yourself to an additional fee when you really need a fully charged car in the morning might be practical.

If the wind farms are only for the night time charging of cars, you still have your conventional capacity, which isn't fully used on evening a hot summer's night. When the area is becalmed this can be used. This is not like the situation with conventional wind/coal mixes, as you don't need to meet needs second by second. If the wind doesn't build up one night you keep the other stations running. If you miscalculate (which people normally do with estimating likely amounts of wind power) you have some time to sort things out, and get capacity on line for a coal/oil/nuclear powered charge.

Cost of 9GW of generation sits around doing nothing on the off chance the wind doesn't blow, or blows too hard, around 9 billion dollars (for CCGT Gas) and that is just the capital cost, not the fuel. 500 million dollars in interest payments alone at around 5% the shareholders will demand.

The wind farm is additional. The backup coal/oil/nuclear isn't. They already have this to meet daytime demands.

Wind turbines meanwhile operate at a real world capacity factor of around 20%, so to meet that 9GW demand it requires 45GW of wind turbine capacity. Cost of that is around 1.6 million dollars per MW capacity (3MW turbine Vestas / Siemens or 4.8 million dollars per turbine) 45GW requires 15000 wind turbines or 72 billion dollars, 3.6 billion dollars in interest payments alone at 5%

A total of 81 billion dollars capital invetsment required to support a population of 5 million vehicles. 16000 dollars per vehicle.

Lots of figures, all roughly in the right ballpark but one thing that keeps cropping up time and time again. Why pay for two sources of energy when just one will do. Mines a nuke. Sits there for months on end just doing the job round the clock. Lasts half a century or more, the entire 'waste' of a 1GW station fits in less space than an olympic swimming pool or can be recycled many times (although digging for new ore and processing it is cheaper) Meanwhile the horizon is unspoilt, there is no noise, the lights stay on.

You have really trivialised the problems of existing nuclear energy. If things like thorium really work out we might not need renewable energy. Current nuclear stations, however, will never be more than a component in a mix of energy sources.

The 20% figure for wind farm utilisation is based on a 24 hour average. If most of your wind occurs at night, and you are only expecting to use it at night, you will have a lot more then 9GW available if you install 45GW of capacity. I think you are massively overestimating the necessary investment in redundant capacity.

I don't know how any of this would work out in the real world, but the fact that it is being promoted by profit making utilities suggests it is worth looking into very seriously.

I think that in general wind power is a stupid idea, unless you come up with some seriously effective storage scheme, which can get you over really long periods of low energy input to the system, and can smooth out the short term highs and lows.

That's a really bizarre argument. Here is a load of clean energy, you just need to make some up-front investment to harvest it and get a massive pay-off. But nah, let's ignore it because it isn't quite as easy as building another coal plant, or because it won't help the power company get richer fast enough.

A more sensible argument would be that we need to improve the grid and our stand-by sources to take advantage of this, and keep building more storage.

Pray, tell us how? If you can really crack the storage problem its pretty straightforward to move to 100% renewable energy.

After reading through this thread and seeing how many people have misunderstood Dave's point. Here's another way of putting it. In economics one of the most rudimentary things to understand is opportunity cost. Opportunity cost is the reasoning Dave is using here. .......

sorry for shortening your post but here's another way of putting it: (dunno if this was prev. menitoned but here it is anyway) in europe solar (and other renewables) are heavilly subsidized by the state(s). so they're not really looking it from that perspective. at all.it's a money losing operation anyway.

i mean take solar power(as a whole, outside this garbage of a road project, which is wrong in so many ways), i don't really think abybody is making any money on it, aside from those making the equipment, ie panels and the rest.the money-return times are just ridiculously long....

i feel solar power is something that's perceived as the thing you "must do", and the thing you'll do because state will help you with, not because it's a way to make money.moving magnets just makes a lot more electric power than photons moving electrons a bit.and, as coppice says, you can't really store it.

i mean mentioning solar and profit in same sentence is silly to me.

a bit more about germany, mojo-cahn said

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Germany is looking to reduce CO2 output by 40% by the mid 2020s. They are on target for that, reducing the number of coal plants and replacing old ones with new cleaner ones.

well, 40% is a nice number, so is 60 and 80%, but it depends on the starting number ie what number you're trying to bring down...the images i linked in my post tend to show most co and co2 over the germany, which can't be a surprise because one would expect them to produce and consume most energy in europe...probably.and if most of it comes from coal-plants, it all adds up nicely....and if france beats them by energy consumption, they're still much cleaner because they use nuclear plants.

so overall, at this point, i don't think world should try to copy germany at its present state, they should avoid coal if at all possible. as for their solar and renewable projects, that's something to copy indeed, but less places have as much money to invest in it.hold on, not 'invest' but 'give away', esentially.

Sorry, in future I'll try only to say things that you agree with and avoid poking holes in your arguments.

You haven't poked any holes in my argument. You just twisted what I said, to make stuff up. You do this to other people, too. Is it intentional, or do you have a problem reading?

I said that if you really solve the storage problem, then getting to 100% renewable energy is very much possible. I did not say that renewables only make sense if you can have 100% renewable energy. That was your invention.

Solving the energy storage problem has two components, because there are two basic problems - short term fluctuations in the energy available from the source, measured in seconds to minutes, and longer term variations in the energy available from the source, measured in days to months (e.g. seasons). If the variation extends to years, you don't really have a viable supply of energy, so storage offers no benefit on that scale.

The reason the two categories of storage timescale need to be treated differently is the focuses are different. If you need to respond to fast fluctuations, the key issue is the responsiveness of the equipment. If you need to respond to slow fluctuations, the key issue is sheer storage, which is the much more difficult problem.

Today we have a mess in which the short term fluctuations are addressable, but people show no interest in addressing them. The long term fluctuations are still a difficult problem. In areas which are suitable for hydro-electric power you can pump water back into the reservoir with renewable energy, and you can generally pump a LOT before you overflow the dam. Large dams aren't a good fit in most places, and where they won't work storing large amounts of energy has defeated us so far.

They seem to be proposing a mixture of fossil fuels with carbon sequestering, and molten salt storage to even out the renewables. The success record to date with both those is not exactly inspiring.

Neither is the success record of coal or nuclear... Fortunately we don't just give up when there are engineering challenges.

That's one of the biggest mistakes that brownies make. They expect everything to work perfectly first time and be a drop-in replacement for existing dirty energy sources. They seem to forget that it took time and money to perfect other energy sources, and would rather just keep polluting and making other people pay the real costs than actually try to improve the environment they share.

Again you are twisting what I said. I responded to Dave saying these people had a compelling and well researched plan. They are proposing unproven solutions, that haven't been looking good so far. That doesn't mean that they can't work, or that further research is unjustified. Research topics don't belong in a plan, though. They wouldn't be research if we knew they were going to turn out well.

You keep hand waving and say "build storage". You can't build stuff when you don't know how to.

After reading through this thread and seeing how many people have misunderstood Dave's point. Here's another way of putting it. In economics one of the most rudimentary things to understand is opportunity cost. Opportunity cost is the reasoning Dave is using here. *snip*

If that is what Dave really meant than all right, true and true.

That is exactly what I was getting at, and is why the entire concept of solar roadways will never be take off.

Quote

But the problem was that he deliberately went out of the way to explain that the whole concept is to put solar panels to the most hostile environment possible and because of that it will never be sustainable.

All of that (and the calculations and comparison with rooftop) was ultimately leading to the final point that ncoonrod14 made about opportunity cost. Although I did not put it quite like he did.